Cylindrical secondary battery having high structural safety and method of manufacturing the same

Abstract

The present invention relates to a cylindrical secondary battery and a manufacturing method thereof. In a cylindrical secondary battery manufactured using an electrode assembly, when a horizontal cross section of a jelly-roll type electrode assembly is divided into a plurality of quadrants, a positive electrode tab and a negative electrode tab are arranged in the same quadrant, whereby the jelly-roll type electrode assembly is controlled to have a uniform diameter, thereby preventing deformation of the positive electrode tab and uneven volume expansion inside the secondary battery due to charging and discharging, to maintain structural stability.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2021-0148568, filed on November 2, 2021, the entire contents of which are incorporated herein by reference.

[0002] This invention relates to a cylindrical secondary battery with high structural safety and a method for manufacturing the same. Background Technology

[0003] As fossil fuels dwindle and energy prices rise, coupled with increasing concerns about environmental pollution, the demand for environmentally friendly alternative energy sources is becoming an indispensable factor in future life. In particular, with technological advancements and the growing demand for mobile devices, the need for secondary batteries as an energy source is rapidly increasing.

[0004] Generally, in terms of battery shape, there is a high demand for prismatic and pouch-shaped secondary batteries, which can be used in products such as mobile phones due to their smaller thickness. In terms of materials, there is a high demand for lithium secondary batteries such as lithium-ion batteries and lithium-ion polymer batteries, which have high energy density, discharge voltage, and output stability.

[0005] Typically, secondary batteries are manufactured by applying an electrode mixture containing electrode active materials to the surface of a current collector to form a positive and a negative electrode, inserting a separator between the positive and negative electrodes to manufacture an electrode assembly, mounting the electrode assembly in a cylindrical or square metal can or an aluminum laminate bag-type casing, and then injecting or impregnating a liquid electrolyte into the electrode assembly or using a solid electrolyte.

[0006] Additionally, secondary batteries can be classified according to the structure of the electrode assembly having a positive / separator / negative electrode structure. Representative examples may include jelly roll type (wound type) electrode assemblies (having a structure in which long sheet-shaped positive and negative electrodes are wound together with a separator inserted therebetween), stacked electrode assemblies (having a structure in which multiple positive and negative electrodes cut into units of a certain size are stacked sequentially with a separator inserted therebetween), and stacked / folded electrode assemblies (having a structure in which dual cells or full cells in which positive and negative electrodes are stacked with a separator inserted therebetween in a specific unit are wound together with a separator sheet).

[0007] Simultaneously, the electrode generates current through ion exchange, and the positive and negative electrodes constituting the electrode have a structure in which electrode active materials are applied to electrode current collectors made of metal. Typically, the negative electrode has a structure in which carbon-based active materials are applied to electrode plates made of copper, aluminum, etc., and the positive electrode has a structure in which active materials made of LiCoO2, LiMnO2, LiNiO2, etc., are applied to electrode plates made of aluminum, etc.

[0008] To manufacture a positive or negative electrode, an electrode mixture containing electrode active material is applied in one direction onto a current collector made of a long metal sheet.

[0009] A separator is placed between the positive and negative electrodes of the battery to insulate them and retain the electrolyte, thereby providing a channel for ion conduction.

[0010] This type of secondary battery is a rechargeable battery made using materials in which a redox process between the material and an electric current is repeatedly performed. Charging occurs when the material undergoes a reduction reaction with an electric current. Discharging occurs when the material undergoes an oxidation reaction. This charging / discharging process is repeated to generate electricity.

[0011] At the same time, unlike prismatic or pouch-shaped secondary batteries, the positive electrode tab of a cylindrical secondary battery is likely to deform when it is repeatedly charged and discharged, which may have a negative impact on the battery's lifespan.

[0012] As mentioned above, when a battery is continuously charged and discharged, the internal structure of the battery becomes unbalanced due to the deformation of the positive electrode tab, which can lead to the disconnection of the electrode tab, uneven internal expansion, etc., which may cause the battery to deteriorate rapidly or burn.

[0013] To address these issues in cylindrical secondary batteries, it is necessary to develop a cylindrical secondary battery in which the positions of the positive and negative electrode tabs are set based on the horizontal cross-section of the wound electrode assembly to maintain the internal uniformity of the secondary battery and prevent deformation due to charging / discharging, thereby achieving stability. Summary of the Invention

[0014] Technical issues

[0015] The purpose of this invention is to provide a cylindrical secondary battery and a method for manufacturing the same. In this cylindrical secondary battery, the positions of the positive and negative electrode tabs of the jelly roll-shaped electrode assembly are specified to prevent deformation of the positive electrode tab due to charging and discharging, and to achieve a uniform internal structure of the secondary battery.

[0016] Technical solution

[0017] This invention provides a cylindrical secondary battery. In one example, the cylindrical secondary battery includes a jelly roll-shaped electrode assembly, a cylindrical housing, and positive and negative electrode tabs connected to the jelly roll-shaped electrode assembly. The cylindrical secondary battery has a structure in which the positive and negative electrode tabs are arranged in the same quadrant when the horizontal cross-section of the winding core perpendicular to the jelly roll-shaped electrode assembly is divided into multiple quadrants.

[0018] In a specific example, the cylindrical secondary battery of the present invention may have a structure in which, on the horizontal cross-section of the jelly roll-shaped electrode assembly, a first radial line from the winding core to the positive electrode tab and a second radial line from the winding core to the negative electrode tab are arranged in the same quadrant of the divided quadrants and are arranged so that they are not collinear with each other.

[0019] In another specific example, the cylindrical secondary battery of the present invention may have a structure in which, on the horizontal cross-section of the jelly roll-shaped electrode assembly, a first radial line from the winding core to the positive electrode tab and a second radial line from the winding core to the negative electrode tab are arranged in the same quadrant of the divided quadrants and form an angle of 15° to 80°.

[0020] In another instance, when the average radius values ​​for each of the four quadrants are calculated and the average radius values ​​between quadrants are compared, the deviation between the average radius values ​​is less than 1%.

[0021] In this case, the deviation between the average radius value of the quadrant in which the positive and negative electrodes are arranged and the average radius value of the quadrant adjacent to the quadrant in which the positive and negative electrodes are arranged is less than 1%.

[0022] In another example, the cylindrical secondary battery of the present invention also includes electrode leads electrically connected to the positive or negative electrode tab by bonding or welding.

[0023] In addition, the present invention provides a method for manufacturing a cylindrical secondary battery. In one example, the method for manufacturing a cylindrical secondary battery of the present invention includes: manufacturing a jelly roll-type electrode assembly, wherein when a horizontal cross-section perpendicular to the winding core is divided into multiple quadrants, the positive electrode tab and the negative electrode tab are arranged in the same quadrant; and inserting the jelly roll-type electrode assembly into a cylindrical battery case and injecting an electrolyte solution into the cylindrical battery case.

[0024] In another example, the manufacture of a jelly roll electrode assembly may include arranging a first radial line from the winding core to the positive electrode tab and a second radial line from the winding core to the negative electrode tab in the same quadrant of a divided quadrant, and ensuring that they are not collinear with each other on the horizontal cross-section of the jelly roll electrode assembly.

[0025] In a specific instance, arranging the first and second radial lines so that they are not collinear may include calculating the expected perimeter of the jelly roll electrode assembly based on the number of windings according to Equation 1 below, and selecting the position of the negative electrode tab from the calculated expected perimeter.

[0026] [Equation 1]

[0027] a n =a n-l +2b

[0028] In equation 1,

[0029] a n This can represent the diameter of each jelly roll type electrode assembly with a corresponding number of windings.

[0030] a n-1 The diameter of the jelly roll-type electrode assembly can represent the number of previous windings.

[0031] b can represent the thickness of the additional repeating layer at the corresponding number of windings.

[0032] n can be an integer greater than or equal to 1, representing the number of windings in the jelly roll electrode assembly; and

[0033] When n is 1, a0 can represent the diameter of the winding core.

[0034] In another specific example, the selection of the negative electrode tab position includes: arranging the positive electrode tab before winding the jelly roll electrode assembly, and arranging the negative electrode tab at a distance from the positive electrode tab calculated by the following Equation 2.

[0035] [Equation 2]

[0036]

[0037] In equation 2,

[0038] L n This can represent the separation distance between the positive and negative electrode tabs on an unwound jelly roll electrode assembly when the first and second radial lines are arranged collinearly.

[0039] a k This can represent the diameter of the wound jelly roll-type electrode assembly; and

[0040] n can be an integer equal to or greater than 1, representing the number of windings in the jelly roll electrode assembly.

[0041] In another example, the selection of the negative electrode tab position may include: placing the positive electrode tab at the starting point of the jelly roll electrode assembly, and placing the negative electrode tab at a distance from the positive electrode sheet calculated by Equation 2.

[0042] Beneficial effects

[0043] In the cylindrical secondary battery of the present invention, the positions of the positive and negative electrode tabs connected to the electrode assembly are specified to control the jelly roll-shaped electrode assembly to have a uniform diameter, thereby preventing deformation of the positive electrode tab and uneven volume expansion inside the secondary battery due to charging and discharging, thus maintaining structural stability. Furthermore, through the manufacturing method of the cylindrical secondary battery of the present invention, the expected circumference is calculated to select the position of the negative electrode tab, ensuring that the positive electrode tab does not overlap with the negative electrode tab. Attached Figure Description

[0044] Figure 1 This is a graph showing the average radius values ​​of each region of the jelly roll-type electrode assembly of Example 1.

[0045] Figure 2 This is a graph showing the average radius values ​​of each region of the jelly roll-type electrode assembly of Embodiment 2.

[0046] Figure 3 This is a graph showing the average radius values ​​of each region of the jelly roll-type electrode assembly of Example 3.

[0047] Figure 4 This is a graph showing the average radius values ​​of each region of the jelly roll-type electrode assembly of Example 4.

[0048] Figure 5 This is a graph showing the average radius values ​​of each region of the jelly roll-type electrode assembly of Comparative Example 1.

[0049] Figure 6 This is a graph showing the average radius values ​​of each region of the jelly roll-type electrode assembly of Comparative Example 2.

[0050] Figure 7 This is a graph showing the average radius values ​​of each region of the jelly roll-type electrode assembly of Comparative Example 3.

[0051] Figure 8 The image shown is a side surface of a cylindrical secondary battery using the jelly roll electrode assembly of Example 3, captured by computed tomography (CT).

[0052] Figure 9 The image shown is a side surface of a cylindrical secondary battery using the jelly roll electrode assembly of Comparative Example 2, obtained by CT imaging.

[0053] Figure 10 The image shown is a vertical CT image captured by using a cylindrical secondary battery with the jelly roll electrode assembly of Example 3 for vertical CT imaging.

[0054] Figure 11 The image shown is a cylindrical secondary battery captured by vertical CT imaging using the jelly roll electrode assembly of Comparative Example 2. Detailed Implementation

[0055] While the present invention is open to various modifications and alternative embodiments, its specific implementation will be described and illustrated by way of examples in the accompanying drawings. However, this is not intended to limit the invention to the specific forms disclosed, but should be understood to include all modifications, equivalents, and substitutions within the spirit and technical scope of the invention.

[0056] In this application, it should be understood that terms such as "comprising" or "having" are intended to indicate the presence of the features, quantities, steps, operations, components, parts, or combinations thereof described in the specification, and they do not preclude the possibility of the presence or addition of one or more other features or quantities, steps, operations, components, parts, or combinations thereof. Furthermore, when a portion such as a layer, membrane, region, or plate is referred to as being "on" another portion, this includes not only the case where the portion is "directly" on the other portion, but also the case where another portion is inserted therein. On the other hand, when a portion such as a layer, membrane, region, or plate is referred to as being "below" another portion, this includes not only the case where the portion is "directly" below the other portion, but also the case where another portion is inserted therein. Additionally, in this application, "arranged on" can include arrangements at the bottom and top.

[0057] The present invention will now be described in detail.

[0058] This invention provides a cylindrical secondary battery and a method for manufacturing the same.

[0059] A conventional cylindrical secondary battery includes a jelly-roll-shaped electrode assembly, a cylindrical housing, and a positive electrode tab and a negative electrode tab connected to the jelly-roll-shaped electrode assembly. In this case, the cylindrical secondary battery is manufactured by arranging the positive and negative electrode tabs to connect to the positive and negative electrodes respectively according to the intended use, inserting the jelly-roll-shaped electrode assembly connecting the positive and negative electrode tabs into the cylindrical housing, injecting electrolyte into the cylindrical housing, and then sealing the cylindrical housing. Unlike the internal structure of a secondary battery, when a cylindrical secondary battery manufactured in this way is repeatedly charged and discharged, there are problems such as deformation of the positive electrode tab and uneven expansion of the wound electrode assembly inside the secondary battery. Therefore, when the internal uniformity is disrupted, the positive electrode tab may break, and the lifespan of the secondary battery may decrease rapidly. Therefore, to solve the above problems, in this invention, when the horizontal cross-section of the wound electrode assembly is divided into multiple quadrants, the wound electrode assembly has a structure in which the positive and negative electrode tabs are arranged in the same quadrant. The positions of the positive and negative electrode tabs are specified to prevent deformation of the positive electrode due to the charging and discharging of the secondary battery, and to increase the uniformity of internal expansion, thereby improving structural stability.

[0060] The cylindrical secondary battery of the present invention will now be described in detail.

[0061] In one embodiment, the cylindrical secondary battery of the present invention comprises a jelly roll-shaped electrode assembly, a cylindrical housing, and positive and negative electrode tabs connected to the jelly roll-shaped electrode assembly. The cylindrical secondary battery may have a structure in which the positive and negative electrode tabs are arranged in the same quadrant when the horizontal cross-section perpendicular to the winding core of the jelly roll-shaped electrode assembly is divided into multiple quadrants.

[0062] Typically, the positive electrode tab connected to the jelly roll-shaped electrode assembly can be configured to protrude from any surface of the horizontal cross-section of the jelly roll-shaped electrode assembly. Additionally, the negative electrode tab can be configured to protrude from a horizontal cross-section opposite to the horizontal cross-section where the positive electrode tab is located. In this case, when the horizontal cross-section of the jelly roll-shaped electrode assembly is divided into multiple quadrants, the positive and negative electrode tabs can be located in the same quadrant.

[0063] As described above, when the positive and negative electrode tabs are located in the same quadrant, the deviation between the average radii of the divided quadrants can be smaller than the deviation when the positive and negative electrode tabs are located in different quadrants. In other words, compared to a jelly roll electrode assembly where the positive and negative electrode tabs are located in different quadrants, a jelly roll electrode assembly where the positive and negative electrode tabs are located in the same quadrant can have a more uniform diameter. Therefore, in a cylindrical secondary battery using a jelly roll electrode assembly with a uniform diameter, deformation of the positive electrode tab caused by continuous charging and discharging is suppressed, and uneven internal expansion of the jelly roll electrode assembly inside the cylindrical secondary battery is minimized, thereby improving the internal structural stability of the cylindrical secondary battery.

[0064] Meanwhile, the cylindrical secondary battery of the present invention has a structure in which, on the horizontal cross-section of the jelly roll-shaped electrode assembly, the first radial line from the winding core to the positive electrode tab and the second radial line from the winding core to the negative electrode tab are arranged in the same quadrant of the divided quadrants and are arranged so that they are not collinear with each other.

[0065] Specifically, the case where the first and second radial lines are arranged collinearly is the case where the positive and negative electrode tabs are arranged collinearly. When the positive and negative electrode tabs are arranged to overlap each other on a single line, the electrode assembly having the quadrant in which the positive and negative electrode tabs are arranged becomes too thick. As a result, the overall deviation between the maximum and minimum radius values ​​of the jelly roll-type electrode assembly increases.

[0066] In another example, the secondary battery of the present invention may have a structure in which, on the horizontal cross-section of the jelly roll-shaped electrode assembly, a first radial line from the winding core to the positive electrode tab and a second radial line from the winding core to the negative electrode tab are arranged in the same quadrant of a divided quadrant and form an angle of 15° to 80°. Specifically, the angle between the first radial line and the second radial line is 20° to 80°, 20° to 60°, or 18° to 45°.

[0067] The secondary battery may have a structure in which, on the horizontal cross-section of the jelly roll-shaped electrode assembly, a first radial line from the winding core to the positive electrode tab and a second radial line from the winding core to the negative electrode tab are arranged in the same quadrant of the divided quadrants and form an angle of 15° to 80°.

[0068] Specifically, when the first and second radial lines are arranged in the same quadrant, the maximum angle between them is 90° and the minimum angle is 0°, which corresponds to the case where the first and second radial lines overlap. In this case, where the first and second radial lines form a jelly-roll-shaped electrode assembly with an angle of 15° to 80°, the deviation between the maximum and minimum radius values ​​of the jelly-roll-shaped electrode assembly is reduced, resulting in an electrode assembly of uniform thickness. This prevents deformation of the positive electrode tab and uneven expansion within the electrode assembly, even during continuous charging and discharging. On the other hand, when the angle between the first and second radial lines is too small, the first and second radial lines are too close to each other. Therefore, the deviation between the average radius value of the quadrant where the first and second radial lines are arranged and the average radius value of other quadrants may increase.

[0069] Furthermore, even when the angle between the first and second radial lines exceeds a certain range, the deviation between the average radius value of the quadrant in which the first and second radial lines are arranged and the average radius value of the other quadrants may increase.

[0070] In another example, in the cylindrical secondary battery of the present invention, when the average radius values ​​of each of the four divided quadrants are calculated and the average radii of the quadrants are compared with each other, the deviation between them can be less than 1%. Specifically, the deviation can be in the range of greater than 0% and less than or equal to 1%, in the range of 0.01% to 0.8%, or in the range of 0.5% to 0.8%. In this case, the thickness difference between the quadrants of the jelly roll-type electrode assembly is reduced to obtain a uniform diameter, thereby improving the uniformity of the internal structure of the cylindrical secondary battery. When the deviation exceeds a certain level, due to the increased thickness difference between the quadrants of the jelly roll-type electrode assembly, it is impossible to prevent uneven expansion inside the cylindrical secondary battery and deformation of the positive electrode tab due to future charging and discharging.

[0071] Furthermore, in the cylindrical secondary battery of the present invention, the deviation between the average radius of the quadrant in which the positive and negative electrode tabs are arranged and the average radius of the quadrant adjacent to the quadrant in which the positive and negative electrode tabs are arranged is less than 1%. Specifically, the deviation can be in the range of greater than 0% and less than or equal to 1%, in the range of 0.01% to 0.8%, or in the range of 0.5% to 0.8%. This is the most preferred condition because a uniform diameter can be obtained by minimizing the thickness difference between the quadrants of the jelly roll-type electrode assembly. Meanwhile, adjacent quadrants are those adjacent to each other in the left-right direction. However, due to the influence of the quadrant in which the positive and negative electrode tabs are arranged, adjacent quadrants may have an increased radius. Therefore, when the deviation between the average radius of the quadrant in which the positive and negative electrodes are arranged and the average radius of the quadrant adjacent to that quadrant is within the above range, the non-uniformity inside the battery can be solved by minimizing the deviation between the average radius of the adjacent quadrant and the quadrant in which the positive and negative electrodes are arranged, and the structural stability of the battery can be ensured during future charging and discharging.

[0072] Furthermore, the deviation between the maximum and minimum radius values ​​of the quadrant where the positive and negative electrodes are arranged can be less than 1%. This is because as the deviation of the radius values ​​in the quadrants where the positive and negative electrodes are arranged decreases, the deviation of the average radius value in each quadrant also decreases. In other words, when the deviation between the maximum and minimum radius values ​​of the quadrants where the positive and negative electrodes are arranged is within the aforementioned range, the desired purpose can be achieved because the jelly roll electrode assembly can be wound while maintaining a uniform diameter.

[0073] Furthermore, the cylindrical secondary battery of the present invention may also include electrode leads electrically connected to the positive or negative electrode tab by bonding or welding. The method of connecting the electrode leads to the positive or negative electrode tab can be any of the conventional bonding or welding methods commonly used by those skilled in the art, and is not limited to any specific process method.

[0074] Meanwhile, in the cylindrical secondary battery of the present invention, the electrode assembly includes a positive electrode, a negative electrode and a separator inserted between the positive electrode and the negative electrode, and the positive electrode and the negative electrode may each include an active material layer on one or both surfaces.

[0075] The structure of the cylindrical secondary battery of the present invention will now be described.

[0076] The secondary battery includes an electrode assembly having a structure in which a negative electrode and a positive electrode are alternately stacked by a separator inserted between the electrodes and impregnated with a non-aqueous electrolyte containing a lithium salt. The electrodes of the secondary battery can be manufactured by applying an electrode mixture containing electrode active materials onto a current collector and then drying the electrode mixture. If necessary, the electrode mixture may optionally further include a binder, conductive material, filler, etc.

[0077] In this invention, the positive electrode current collector is typically formed with a thickness of 3 μm to 500 μm. The material of the positive electrode current collector is not particularly limited, as long as it has high conductivity and does not cause adverse chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, or sintered carbon can be used, or copper or stainless steel surface-treated with carbon, nickel, titanium, or silver. Fine irregularities can be formed on the surface of the current collector to increase the adhesion of the positive electrode active material. The current collector can be any of various forms such as film, sheet, foil, mesh, porous body, foam, nonwoven fabric, etc.

[0078] The negative electrode current collector sheet is typically formed with a thickness ranging from 3 μm to 500 μm. The material of the negative electrode current collector is not particularly limited, as long as it has high conductivity and does not cause adverse chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, or sintered carbon can be used, or copper or stainless steel surface-treated with carbon, nickel, titanium, or silver, or aluminum-cadmium alloys. Furthermore, similar to the positive electrode current collector, fine irregularities can be formed on the surface of the negative electrode current collector to increase the adhesion of the negative electrode active material. The negative electrode current collector can take any of various forms, such as a film, sheet, foil, mesh, porous body, foam, or nonwoven fabric.

[0079] In this invention, the positive electrode active material is a material capable of inducing an electrochemical reaction, and is a lithium transition metal oxide containing two or more transition metals. Examples include layered compounds, such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2) substituted with one or more transition metals, lithium manganese oxide substituted with one or more transition metals, and compounds of the formula LiNi... 1-y M y Lithium-nickel based oxides represented by O2 (where M is Co, Mn, Al, Cu, Fe, Mg, B, Cr, Zn, or Ga and contains at least one element selected from the above, and 0.01 ≤ y ≤ 0.7), and those composed of elements such as Li 1+z Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2 or Li 1+ z Ni 0.4 Mn 0.4 Co 0.2 O2 and other formulas Li 1+zNi b Mn c Co 1-(b+c+d) M d O (2-e) A e (where -0.5 ≤ z ≤ 0.5, 0.1 ≤ b ≤ 0.8, 0.1 ≤ c ≤ 0.8, 0 ≤ d ≤ 0.2, 0 ≤ e ≤ 0.2, b + c + d < 1, M is Al, Mg, Cr, Ti, Si or Y, and A is F, P or Cl) represents a lithium-nickel-cobalt-manganese composite oxide and a lithium metal phosphate of the formula Li 1+x M 1-y M’ y PO 4-z X z (where M is a transition metal, and preferably Fe, Mn, Co or Ni, M’ is Al, Mg or Ti, X is F, S or N, -0.5 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5, 0 ≤ z ≤ 0.1), but the present invention is not limited thereto.

[0080] Examples of the negative electrode active material include carbon such as non-graphitized carbon or graphitic carbon, metal composite oxides such as Li x Fe2O3 (0 ≤ x ≤ 1), LixWO2 (0 ≤ x ≤ 1) or Sn x Me 1-x Me’ y O z (where Me is Mn, Fe, Pb or Ge, Me’ is Al, B, P, Si, an element of Group 1, 2 or 3 of the periodic table, or a halogen, 0 < x ≤ 1, 1 ≤ y ≤ 3, 1 ≤ z ≤ 8), lithium metal, lithium alloy, silicon-based alloy, tin-based alloy, metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4 or Bi2O5, conductive polymers such as polyacetylene, and Li-Co-Ni-based materials.

[0081] Based on the total weight of the mixture containing the positive electrode active material, the conductive material is usually added in an amount of 1 wt% to 30 wt%. The conductive material is not particularly limited as long as it has high conductivity and does not cause chemical changes in the battery. Examples of the conductive material may include: graphite, such as natural graphite or synthetic graphite; carbon black, such as acetylene black, Ketjen black, channel black, furnace black, lamp black or thermal cracking carbon black; conductive fibers, such as carbon fibers or metal fibers; metal powders, such as carbon fluoride powder, aluminum powder or nickel powder; conductive whiskers, such as zinc oxide or potassium titanate; conductive metal oxides, such as titanium oxide; and conductive materials, such as polyphenylene derivatives.

[0082] The adhesive can be a component that facilitates adhesion between the conductive material, the active material, and the current collector, and its content is typically from 1% to 30% by weight based on the total weight of the mixture containing the negative electrode active material. Examples of adhesives may include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, and various copolymers.

[0083] Fillers are materials used to control electrode expansion and are optionally used. Fillers are not particularly limited, provided they are fibrous materials that do not cause chemical changes in the battery. Examples of fillers may include olefin polymers such as polyethylene or polypropylene, and fibrous materials such as glass fiber or carbon fiber.

[0084] Other components, such as viscosity modifiers and adhesion promoters, may optionally be added or added in combination of two or more. Viscosity modifiers are components used to adjust the viscosity of the electrode mixture to promote mixing of the electrode mixture and its coating on the current collector, and may be added up to 30% by weight based on the total weight of the negative electrode mixture. Examples of viscosity modifiers include carboxymethyl cellulose, polyvinylidene fluoride, etc., but the invention is not limited thereto. In some cases, solvents may also be used as viscosity modifiers.

[0085] Adhesion promoters are added auxiliary components used to enhance the adhesion between the active material and the current collector. They can be added in amounts less than 10% by weight, based on the weight of the adhesive. Examples of adhesion promoters may include oxalic acid, adipic acid, formic acid, acrylic acid derivatives, and itaconic acid derivatives.

[0086] A separator is inserted between the positive and negative electrodes and is made of an insulating ultrathin film with high ion permeability and high mechanical strength. The pore size of the separator is typically in the range of 0.01 μm to 10 μm, and its thickness is typically in the range of 5 μm to 300 μm. As a separator, for example, sheets or nonwoven fabrics made of olefin polymers (such as polypropylene, glass fiber, or polyethylene) with chemical resistance and hydrophobicity are used.

[0087] Non-aqueous electrolytes containing lithium salts comprise both the electrolyte and the lithium salt. Non-aqueous organic solvents, organic solid electrolytes, and inorganic solid electrolytes are used as electrolytes.

[0088] Examples of non-aqueous organic solvents may include: aprotic organic solvents such as N-methyl-2-pyrrolidone, propylene carbonate, ethylene carbonate, butyl carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, triphosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolium ketone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl propionate, or ethyl propionate.

[0089] Examples of organic solid electrolytes may include polyethylene derivatives, polyoxyethylene derivatives, polyoxypropylene derivatives, phosphate polymers, polylyzed lysine, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, and polymers containing ion-dissociating groups.

[0090] Examples of inorganic solid electrolytes may include lithium (Li) nitrides, halides, and sulfates, such as Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4, Li4SiO4-LiI-LiOH, and Li3PO4-Li2S-SiS2.

[0091] Lithium salts are materials that are readily soluble in non-aqueous electrolytes. Examples include LiCl, LiBr, LiI, LiClO4, LiBF4, and LiB2. 10 Cl 10 LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, (CF3SO2)2NLi, lithium chloroborane, lithium lower aliphatic carboxylic acids, lithium tetraphenylborate, and imides.

[0092] In addition, to improve charge / discharge characteristics and flame retardancy, substances such as pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, N-glycol dimethyl ether (glyme), triammonium hexaphosphate, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolides, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, and aluminum trichloride can be added to the electrolyte. In some cases, to impart non-flammability, the electrolyte may also contain halogen-containing solvents such as carbon tetrachloride or trifluoroethylene. Furthermore, to improve high-temperature storage characteristics, the electrolyte may also contain carbon dioxide gas, fluoroethylene carbonate (FEC), propylene sulpholactone (PRS), and fluoropropylene carbonate (FPC).

[0093] In an exemplary instance, a lithium salt, such as LiPF6, LiClO4, LiBF4, or LiN(SO2CF3)2, is added to a mixed solvent of cyclic carbonates, such as ethylene carbonate (EC) or propylene carbonate (PC), as a high dielectric solvent, and linear carbonates, such as diethyl carbonate (DEC), dimethyl carbonate (DMC), or ethyl methyl carbonate (EMC), as a low viscosity solvent, to prepare a non-aqueous electrolyte containing lithium salts.

[0094] In addition, the present invention provides a method for manufacturing a cylindrical secondary battery.

[0095] Meanwhile, the manufacturing method of the cylindrical secondary battery may include content that overlaps with the above-described cylindrical secondary battery, and redundant descriptions will be omitted.

[0096] In one example, the method of manufacturing the cylindrical secondary battery of the present invention may include manufacturing a jelly roll-shaped electrode assembly (wherein, when the horizontal cross-section perpendicular to the winding core is divided into multiple quadrants, the positive electrode tab and the negative electrode tab are disposed in the same quadrant), inserting the jelly roll-shaped electrode assembly into a cylindrical battery case, and injecting an electrolyte solution into the cylindrical battery case.

[0097] In another example, the manufacture of the jelly roll type electrode assembly includes arranging a first radial line from the winding core to the positive electrode tab and a second radial line from the winding core to the negative electrode tab in the same quadrant of a divided quadrant and not collinear with each other on the horizontal cross-section of the jelly roll type electrode assembly. As described above, when the first and second radial lines are arranged collinear with each other, the average radius value of the same quadrant in which the positive and negative electrodes are arranged increases excessively compared to the quadrant in which the positive and negative electrodes are not arranged, due to the thickness of the positive electrode tab arranged on the first radial line and the negative electrode tab arranged on the second radial line. Therefore, the non-uniformity of the inner diameter of the jelly roll type electrode assembly increases. Therefore, the problem to be solved in this invention, namely, the problem of uneven expansion inside the electrode assembly and deformation of the central axis of the positive electrode tab of the cylindrical secondary battery due to charging and discharging, cannot be solved. Therefore, the present invention is characterized by the fact that the positive and negative electrodes are not collinear with each other even when arranged in the same quadrant.

[0098] In another example, in the method of manufacturing the cylindrical secondary battery of the present invention, arranging the first radial line and the second radial line so that they are not collinear with each other may include calculating the expected circumference of the jelly roll-shaped electrode assembly based on the number of windings according to the following Equation 1 and selecting the position of the negative electrode tab from the calculated expected circumference.

[0099] [Equation 1]

[0100] a n =a n- 1+2b

[0101] In equation 1, a n a represents the diameter of the jelly roll electrode assembly for each corresponding number of windings. n-1 a represents the diameter of the jelly roll-type electrode assembly for each preceding winding number, b represents the thickness of the repeating layer added at the corresponding winding number, n is an integer greater than or equal to 1 and represents the number of windings of the electrode assembly, and when n is 1, a0 represents the diameter of the winding core.

[0102] The repeating layer includes a positive electrode, a negative electrode, and a separator inserted between the positive and negative electrodes, and the positive and negative electrodes may each include an active material layer on one or both surfaces. In this case, the configuration of the repeating layer can be set in various ways depending on the manufacturing conditions, and therefore can be appropriately changed.

[0103] For example, the perimeter can be a circle formed by using the point where the first radial line lies as the starting point and the return point. On the other hand, the starting point and the return point can be the same point, and can be any point.

[0104] The diameter can be calculated by applying an arithmetic sequence to the diameter formed by adding the diameter of the repeating layer to the initial core diameter, and the expected circumference can be calculated based on the calculated diameter.

[0105] In specific examples, when there is no repeating layer, i.e., when the electrode assembly is not wound, the diameter can be the diameter of the winding core. When there is one repeating layer, i.e., when the jelly-rolled electrode assembly around the winding core is wound once, the expected circumference can be calculated using the diameter obtained by adding the diameter of the winding core to the value obtained by multiplying the thickness of the repeating layer by an integer two. Furthermore, when there are two repeating layers, i.e., when the jelly-rolled electrode assembly around the winding core is wound twice, the expected circumference can be calculated using the diameter calculated when there is one repeating layer to the value obtained by multiplying the thickness of the repeating layer by an integer two. The position of the negative electrode tab can be selected from the expected circumference calculated in this way.

[0106] In another example, the selection of the negative electrode tab position includes arranging the positive electrode tab before winding the electrode assembly and arranging the negative electrode tab at a distance from the positive electrode tab calculated by the following Equation 2.

[0107] [Equation 2]

[0108]

[0109] In equation 2, L n a represents the separation distance between the positive and negative tabs on an unwound jelly roll electrode assembly when the first and second radial lines are arranged collinearly. kThe diameter of the wound jelly roll electrode assembly is indicated by n, which is an integer equal to or greater than 1, and represents the number of windings in the electrode assembly.

[0110] In equation 2, L n This represents the distance between the positive and negative tabs of the unwound jelly roll electrode assembly when the first and second radial lines are arranged collinear with respect to each other. The negative tab can be located at a position other than where the positive and negative tabs are spaced apart from each other by the distance calculated from Equation 2 above.

[0111] As described above, using Equation 2, based on the number of windings, when the first radial line on which the positive electrode tab is arranged overlaps with the second radial line on which the negative electrode tab is arranged, the distance between the positive and negative electrode tabs on the unwound electrode assembly can be easily calculated. Therefore, it is possible to prevent the negative electrode tab from being set collinear with the positive electrode tab to overlap with it.

[0112] Therefore, according to the present invention, the expected circumference of the wound electrode assembly can be calculated based on the number of windings in Equation 1, and based on the distance between the positive and negative electrode tabs calculated by Equations 1 and 2, the positive and negative electrode tabs can be arranged in the same quadrant and can be arranged to be non-collinear with each other. Therefore, in a cylindrical secondary battery using a jelly-roll-type electrode assembly wound with uniform thickness by minimizing the deviation between the average radius values ​​of the quadrants divided by a horizontal cross-section perpendicular to the winding core, internal imbalance of the cylindrical secondary battery and deformation of the central axis of the positive electrode tab due to charging and discharging can be prevented.

[0113] Example

[0114] The invention will be described in more detail below with reference to the accompanying drawings. While the invention is open to various modifications and alternative embodiments, its specific implementation will be described and illustrated by way of example in the drawings. However, this is not intended to limit the invention to the specific forms disclosed, but should be understood to include all modifications, equivalents, and substitutions within the spirit and scope of the invention.

[0115] (Examples and Comparative Examples)

[0116] <Manufacturing of Jelly Roll-Type Electrode Components>

[0117] N-methylpyrrolidone was injected into a homogeneous mixer, and 97.8 parts by weight of LiNi were weighed and introduced as the positive electrode active material based on 100 parts by weight of the solids of the positive electrode slurry. 0.6 CO 0.2 Mn 0.2O2, 0.7 parts by weight of carbon black as a conductive material, and 1.5 parts by weight of polyvinylidene fluoride (PVDF) as a binder were mixed at 2,000 rpm for 60 minutes to prepare a positive electrode slurry for lithium secondary batteries. The prepared positive electrode slurry was applied to both surfaces of an aluminum sheet, dried, and then rolled to manufacture the positive electrode.

[0118] Simultaneously, 86 parts by weight of artificial graphite and 10 parts by weight of silicon (Si) particles as the negative electrode active material, 2 parts by weight of carbon black as the conductive material, and 2 parts by weight of styrene-butadiene rubber (SBR) and carbonyl methyl cellulose (CMC) as binders were weighed out, introduced, and mixed at 2,000 rpm for 60 minutes to prepare a negative electrode slurry for lithium secondary batteries. The negative electrode slurry was applied to both surfaces of a thin copper plate with an average thickness of 10 μm, dried, and then rolled to manufacture a negative electrode for a jelly roll electrode assembly.

[0119] A porous polyethylene (PE) membrane with an average thickness of 20 μm is inserted between the manufactured positive and negative electrodes to create a jelly roll electrode assembly.

[0120] Next, the positive electrode tab is placed on the uncoated area of ​​the positive electrode of the jelly roll electrode assembly. When the horizontal cross-section of the jelly roll electrode assembly is divided into multiple quadrants, based on the position of the hour hand on a clock, the area from 9 o'clock to 12 o'clock is the first quadrant, the area from 12 o'clock to 3 o'clock is the second quadrant, the area from 3 o'clock to 6 o'clock is the third quadrant, and the area from 6 o'clock to 9 o'clock is the fourth quadrant. In this case, the positive electrode tab is placed on the center line of the first quadrant, and the negative electrode tab is placed as shown in the embodiments and comparative examples in Table 1 below.

[0121] The angle between the first radial line and the second radial line in Table 1 below is the angle between the first radial line from the winding core to the positive electrode tab and the second radial line from the winding core to the negative electrode tab in the horizontal cross-sectional direction of the jelly roll electrode assembly.

[0122] [Table 1]

[0123] Classification Position of the negative electrode tab The angle between the first radial line and the second radial line Example 1 First Quadrant 0° Example 2 First Quadrant 20° Example 3 First Quadrant 30° Example 4 First Quadrant 40° Comparative Example 1 Second Quadrant 90° Comparative Example 2 Third Quadrant 180° Comparative Example 3 Fourth Quadrant 90°

[0124] (Experimental Example)

[0125] To evaluate the performance of the jelly roll-type electrode assembly of the cylindrical secondary battery of the present invention, the following experiments were conducted.

[0126] <Calculate the diameter and deviation of the jelly roll electrode assembly>

[0127] The jelly roll-type electrode assemblies manufactured in Examples 1 to 4 and Comparative Examples 1 to 3 were wound around. The average radius values ​​between quadrants of the jelly roll-type electrode assemblies were calculated based on the position of the negative electrode tab, and the maximum deviation among the deviations of the average radii between quadrants was calculated. The results are shown in Table 2 below. Figures 1 to 7 middle.

[0128] [Table 2]

[0129]

[0130] As shown in Table 2 and Figures 1 to 7 As shown, when the positive and negative electrodes of Examples 2 to 4 are arranged in the same quadrant, the maximum value of the deviation between the average radii of the quadrants is smaller than that when the positive and negative electrodes are arranged in different quadrants.

[0131] Meanwhile, in Example 1, the first radial line and the second radial line overlap each other, and the maximum deviation value is the largest in Examples 2 to 4.

[0132] Furthermore, in Example 3 of Examples 1 to 4, the maximum deviation value was the smallest. Therefore, it can be confirmed that even when the positive and negative electrode tabs are arranged in the same quadrant, the inner diameter of the jelly roll electrode assembly is formed most uniformly when the first radial line and the second radial line form an average angle of 30°.

[0133] On the other hand, in Comparative Examples 1 to 3, where the positive and negative electrodes are arranged in different quadrants, the deviation is greatest in Comparative Example 2. Therefore, it can be confirmed that when the positive and negative electrodes are arranged as in Comparative Example 2, the inner diameter of the jelly roll electrode assembly is the most uneven.

[0134] <Evaluation of Internal Disconnection>

[0135] The jelly roll-shaped electrode assemblies manufactured in Examples 1 to 4 and Comparative Examples 1 to 3 were wound and inserted into a cylindrical housing, and electrolyte was injected to manufacture a cylindrical secondary battery. Then, the internal disconnection of each manufactured cylindrical secondary battery was evaluated.

[0136] Specifically, each manufactured cylindrical secondary battery was charged and discharged 200 times in constant current / constant voltage (CC / CV) mode, and then disassembled to check whether the negative terminal in the secondary battery was disconnected. In this case, it was charged at a constant current of 1C until the voltage reached 4.25V, and discharged at a constant current of 1C until the voltage reached 2.5V. The results are shown in Table 3 below.

[0137] [Table 3]

[0138] Classification Disconnection occurred Example 1 none Example 2 none Example 3 none Example 4 none Comparative Example 1 none Comparative Example 2 yes Comparative Example 3 none

[0139] As shown in Table 3, no internal disconnection occurred in Examples 1 to 4 and Comparative Examples 1 and 3, while an internal disconnection occurred in Comparative Example 2. Therefore, in the case of Comparative Example 2, it can be confirmed that the internal disconnection occurred due to uneven expansion and deformation inside the electrode assembly.

[0140] <Evaluation of Charge / Discharge Life>

[0141] The jelly-roll-type electrode assemblies manufactured in Examples 1 to 4 and Comparative Examples 1 to 3 were wound and inserted into a cylindrical housing, and electrolyte was injected to manufacture a cylindrical secondary battery. The batteries were charged at 45°C in 0.33C CC mode until the voltage reached 4.23V. Then, they were discharged in 0.33C CC mode until the voltage reached 2.5V, and then further discharged in CV mode until the current value decreased to 0.05% of the initial current value to check the first discharge capacity.

[0142] Then, the same charge / discharge operation was performed 200 times. The discharge capacity of the last measurement was divided by the discharge capacity of the first measurement to calculate the charge / discharge capacity retention rate of 0.33C. The results are shown in Table 4 below.

[0143] [Table 4]

[0144] Classification Capacity retention rate (%) Example 1 91.2 Example 2 96.9 Example 3 99.1 Example 4 97.4 Comparative Example 1 91.7 Comparative Example 2 88.7 Comparative Example 3 89.8

[0145] As shown in Table 4, the capacity retention rate was higher in Examples 1 to 4 than in Comparative Examples 1 to 3. Therefore, it can be seen that a high capacity retention rate is exhibited when the positive and negative electrode tabs are arranged in the same quadrant. On the other hand, the capacity retention rate is lower when the positive and negative electrode tabs are placed collinearly as in Example 1. Furthermore, in Comparative Examples 1 to 3, the lowest capacity retention rate was observed in Comparative Example 2.

[0146] Based on the above results, as in Examples 2 to 4, when the positive electrode tab and the negative electrode tab are arranged in the same quadrant and maintain a certain distance, it can be seen that the uniformity of the inner diameter of the jelly roll-shaped electrode assembly is improved, which disperses the stress generated in the outer part and greatly reduces the stress accumulated in the electrode assembly, thereby preventing damage to the electrode from continuous charging and discharging.

[0147] <Evaluation of Shaft Deformation of Positive Electrode>

[0148] The jelly-roll-type electrode assemblies manufactured in Example 3 and Comparative Example 2 were each wound and inserted into a cylindrical housing, and electrolyte was injected to manufacture a cylindrical secondary battery. After performing 50 and 100 charge-discharge cycles on each manufactured cylindrical secondary battery, CT (computed tomography) scans were performed on the cylindrical secondary batteries. The results showed... Figures 8 to 11middle.

[0149] Figure 8 and Figure 9 The tilt of the central axis a and imaginary axis b of the positive electrode tab of a cylindrical secondary battery using the jelly roll-shaped electrode assembly manufactured in Example 3 and Comparative Example 2 is shown. Figure 10 and Figure 11 The internal expansion degree of the jelly roll-shaped electrode assembly manufactured in Example 3 and Comparative Example 2 and the deformation degree of the positive electrode tab are shown.

[0150] refer to Figure 8 Even when the cylindrical secondary battery is charged 50 and 100 times, the positive electrode tab 10 will not deform because its central axis a and imaginary axis b are parallel to each other. Additionally, refer to... Figure 10 Even after 50 and 100 charge-discharge cycles of the cylindrical secondary battery, no deformation of the positive electrode tab 10 and negative electrode tab 20 occurs. This confirms that... Figure 11 In contrast, the expansion of the electrode assembly in a cylindrical secondary battery is relatively uniform.

[0151] At the same time, refer to Figure 9 When the cylindrical secondary battery is charged and discharged 50 times, it can be confirmed that the imaginary axis b of the positive electrode tab 10 is tilted relative to the central axis a of the cylindrical secondary battery. Furthermore, when the cylindrical secondary battery is charged and discharged 100 times, the fact that the imaginary axis b of the positive electrode tab 10 is more tilted than the central axis a indicates that the positive electrode tab 10 has deformed. Additionally, refer to... Figure 11 When the cylindrical secondary battery was charged and discharged 50 and 100 times, the negative electrode tab 20 did not deform, but the positive electrode tab 10 deformed. This confirms that... Figure 9 In contrast, the expansion within the electrode assembly of a cylindrical secondary battery is relatively significantly biased and uneven in one direction.

[0152] Based on the above results, when the cylindrical secondary battery of the present invention is a secondary battery having a structure in which the positive electrode tab and the negative electrode tab are arranged in the same quadrant when the horizontal cross-section of the jelly roll-shaped electrode assembly is divided into several quadrants, and the first radial line from the winding core to the positive electrode tab and the second radial line to the negative electrode tab do not overlap with each other, the cylindrical secondary battery has a structure that minimizes the inner diameter deviation of the electrode assembly. Even when the cylindrical secondary battery with this structure is continuously charged and discharged, it can be seen that the positive electrode tab does not deform, and the structural stability is improved due to the uniform internal expansion, thereby maintaining high energy efficiency.

[0153] Although exemplary embodiments of the invention have been described with reference to the accompanying drawings, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as defined by the appended claims.

[0154] Therefore, the scope of the present invention should not be limited by the content described in the detailed description of the specification, but should be defined by the claims.

[0155] <Explanation of Figure Markers>

[0156] 10: Positive electrode tab

[0157] 20: Negative electrode tab

Claims

1. A cylindrical secondary battery, comprising: Jelly roll type electrode assembly; Cylindrical shell; and The positive and negative electrodes are connected to the jelly roll-shaped electrode assembly. Wherein, when the horizontal cross-section of the winding core perpendicular to the jelly-roll-shaped electrode assembly is divided into multiple quadrants, the cylindrical secondary battery has a structure in which the positive electrode tab and the negative electrode tab are arranged in the same quadrant. The cylindrical secondary battery has a structure in which, on the horizontal cross-section of the jelly-roll-shaped electrode assembly, a first radial line from the winding core to the positive electrode tab and a second radial line from the winding core to the negative electrode tab are arranged in the same quadrant of a divided quadrant, forming an angle of 15° to 40°. Specifically, when calculating the average radius value of each of the four divided quadrants and comparing the average radius values ​​between the quadrants, the deviation between the average radius values ​​is less than 1%.

2. The cylindrical secondary battery as described in claim 1, wherein, The cylindrical secondary battery has a structure in which, on the horizontal cross-section of the jelly roll-shaped electrode assembly, a first radial line from the winding core to the positive electrode tab and a second radial line from the winding core to the negative electrode tab are arranged in the same quadrant of the divided quadrants and form an angle of 20° to 40°.

3. The cylindrical secondary battery as described in claim 1, wherein, When the average radius values ​​of the four divided quadrants are calculated and the average radius values ​​between quadrants are compared with each other, the deviation between the average radius values ​​is 0.01% to 0.8%.

4. The cylindrical secondary battery as described in claim 3, wherein, The deviation between the average radius of the quadrant where the positive and negative electrodes are arranged and the average radius of the quadrant adjacent to the quadrant where the positive and negative electrodes are arranged is less than 1%.

5. The cylindrical secondary battery as claimed in claim 1, further comprising electrode leads electrically connected to the positive or negative electrode tab by bonding or welding.

6. A method for manufacturing a cylindrical secondary battery, the method comprising: Manufacturing a jelly roll-type electrode assembly, wherein when the horizontal cross-section perpendicular to the winding core is divided into multiple quadrants, the positive electrode tab and the negative electrode tab are arranged in the same quadrant; and The jelly-roll-shaped electrode assembly is inserted into the cylindrical battery casing, and the electrolyte solution is injected into the cylindrical battery casing. The cylindrical secondary battery has a structure in which, on the horizontal cross-section of the jelly-roll-shaped electrode assembly, a first radial line from the winding core to the positive electrode tab and a second radial line from the winding core to the negative electrode tab are arranged in the same quadrant of a divided quadrant, forming an angle of 15° to 40°. Specifically, when calculating the average radius value of each of the four divided quadrants and comparing the average radius values ​​between the quadrants, the deviation between the average radius values ​​is less than 1%.

7. The method of claim 6, wherein, The arrangement of the first radial line and the second radial line includes: The expected circumference of the jelly roll electrode assembly is calculated based on the number of windings according to Equation 1 below; and Choose the position of the negative electrode tab based on the calculated expected perimeter: [Equation 1] In equation 1, a n This indicates the diameter of the jelly roll electrode assembly for each corresponding number of windings; a n-1 The diameter of the jelly roll electrode assembly for each preceding winding number; b represents the thickness of the repeating layer added at the corresponding number of windings; n is an integer greater than or equal to 1, and represents the number of windings in the jelly roll electrode assembly; and When n is 1, a0 represents the diameter of the winding core.

8. The method of claim 7, wherein, The selection of the negative electrode tab position includes: arranging the positive electrode tab before winding the jelly-shaped electrode assembly, and arranging the negative electrode tab at a distance from the positive electrode tab calculated by the following equation 2: [Equation 2] In equation 2, L n This indicates the separation distance between the positive and negative electrode tabs on an unwound jelly roll electrode assembly when the first and second radial lines are arranged collinearly with each other. a k Indicates the diameter of the wound jelly roll electrode assembly; and n is an integer equal to or greater than 1, and represents the number of windings of the jelly roll electrode assembly.

9. The method of claim 8, wherein, The selection of the negative electrode tab position includes: placing the positive electrode tab at the starting point of the jelly roll electrode assembly, and placing the negative electrode tab at a distance from the positive electrode tab calculated by Equation 2.

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